The Vile Village by Lemony Snicket

In the seventh book in the series, Lemony Snicket heightens tension by introducing his own brother, if only briefly. The Quagmire triplets are rescued, but still don't get to share their information about VFD, and the Baudelaire Orphans are framed for a murder by the end of the novel. This series gets more and more sophisticated as it continues.